ruby write json file from an object

Question

I'm getting an error expected ':' after property name in object at line 1 column 15 how can I get rid of '=>'? when I replace "=>" by ":" in the to_json methods I'm getting an error syntax error, unexpected ':', expecting =>

require 'json'    
class Province
        attr_accessor :provOrigine, :destination, :total, 
                        :q1, :q2, :q3, :q4

        def initialize(line)
            @provOrigine =  line.split(';').first.split(",").first
            @destination =  line.split(';').at(1).split(',').first
            @q1 = (line.split(';').at(4)).to_i
            @q2 = (line.split(';').at(5)).to_i
            @q3 = (line.split(';').at(6)).to_i
            @q4 = (line.split(';').at(7)).to_i
        end
        def to_json
          {'provOrigine' => @provOrigine.to_s, 'destination' => @destination.to_s, 'q1' => @q1.to_s, 'q2' => @q2.to_s, 'q3' => @q3.to_s, 'q4' => @q4.to_s}
        end


    end

... prov_instances = contains All the instances of Province ...

File.open("file_json_complete.json", "w") do |f|
  prov_instances.each do |n|
    f.write(n.to_json)
  end
end

this is the result I'm getting

    {"provOrigine"=>"Alberta", "destination"=>"Terre-Neuve-et-Labrador", "q1"=>"777", "q2"=>"1089", "q3"=>"553", "q4"=>"474"}{"provOrigine"=>"Alberta", "destination"=>"Nunavut", "q1"=>"24", "q2"=>"70", "q3"=>"29", "q4"=>"29"}{"provOrigine"=>"Alberta", "destination"=>"Île-du-Prince-Édouard", "q1"=>"116", "q2"=>"69", "q3"=>"150", "q4"=>"64" 
}

and there is no commas between each object?

Philip Hallstrom · Accepted Answer · 2014-09-18 23:51:52Z

13

You'd need to add the commas yourself. f.write(n.to_json) is going to write out a single Province. It has no way to know you're going to keep writing more and need a comma.

Is there a reason you can't do this instead?

File.open('file_json_complete.json', 'w') do |f|
  f.puts prov_instances.to_json
end

answered Sep 18, 2014 at 23:51

Philip Hallstrom

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1 Comment

Papouche Guinslyzinho Over a year ago

Thanks Phillip but the output of your answer is "#<Province:0x8c40f10>","#<Province:0x8c352dc>" it's seems that I really need to append .to_json(*a) inside of the method to_json

Papouche Guinslyzinho · Accepted Answer · 2014-09-18 23:59:33Z

5

I needed to take the hash {} and cast it to_json in order to create a json string

       class Province
         def to_json(*a)
           {'provOrigine' => @provOrigine.to_s, 
            'destination' => @destination.to_s, 
            'q1' => @q1.to_s, 'q2' => @q2.to_s, 
            'q3' => @q3.to_s, 'q4' => @q4.to_s
           }.to_json(*a)

         end
       end

I don't need to loop thought each instances. I could take the object Array and cast it to_json

File.open("file_json_complete.json", "w") do |f|
   f.write(prov_instances.to_json)
end

edited Sep 18, 2014 at 23:59

answered Sep 18, 2014 at 23:52

Papouche Guinslyzinho

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